Fig. 1. Schematic of the proposed passively Q-switched and gain-switched fiber laser.

Fig. 2. (a) Experimental setup for nonlinear absorption measurement of the TDF-SA and (b) nonlinear characterization of the TDF-SA.

Fig. 3. Optical spectra and pulses of the QS and GS fiber laser. (a) Spectrum of EYDCF laser QS centered at 1546 nm and 1561 nm and GS at 1862 nm. (b) Corresponding multi-wavelength first laser line. (c) Corresponding multi-wavelength second laser line. (d) Transmission through the multi-mode TDF to single-mode fiber arrangement. (e) Trains of pulses measured with two photodetectors.

Fig. 4. Profiles of the pulses filtered and unfiltered with the monochromator. (a) 1544.2 nm, (b) 1559.56 nm, and (c) 1862 nm.

Fig. 5. Measured laser pulses at different pump powers. (a) 1544.42 nm, (b) 1559.56 nm, and (c) 1862 nm.

Fig. 6. Separation between pulses decreases as the pump power increases.

Fig. 7. Characteristics of the PQS and GS laser operation. (a) Pulse duration versus pump power and (b) repetition rate versus pump power.

Fig. 8. Blinking of TDF with different pump powers of (a) 7.5 W, (b) 7.75 W, and (c) 7.98 W.